Environmental issues

A modification of the Malmquist index produces a productivity index which is capable of highlighting reductions in undesirable outputs alongside increases in good outputs. The new index, called the Malmquist-Luenberger index, incorporates a directional distance function. It gives credit to firms which reduce unwanted outputs, including pollution, by indicating true productivity improvements over time, and it allows firms to compare themselves to best practices. An application of the index to productivity data from the Swedish paper industry indicates its capabilities.

A microcosm approach to the detection of the effects of herbicide spray in plant communities

Article Abstract:

A microcosm approach using standardized artificial communities of eight dicotyledons with and without a grass was used to determine the effects of spray drift in plant communities. Species yield, flowering performance, seed production, seed viability, and invasion by new species were considered to measure the effects of differential herbicide exposure downwind of the sprayer. Damaging effects were observed and an 8 m buffer zone was suggested as adequate to protect sensitive habitats against deleterious impacts of community processes.

Minimizing investment in residual growing stock for an uneven-aged stand with a target basal area constraint - an approach

Article Abstract:

A non-linear optimization model based on the Lagrangian method uses a target basal area to focus on scaling down investment in growing stock for an uneven-aged stand. Given a unitary change in basal area constraints, the model specifies the optimal DeLiocourt's ratio (q), the number of trees by DBH class and the total investment as well as changes in investment in residual growing stock. The flexible procedure can be used for sensitivity analyses in the event of changes in parameters.